Ferrosilicate proppant and granule composition

ABSTRACT

There is provided a process for the thermal conversion of non-ferrous smelting slag to granular products having sufficient strength and other useful characteristics for use as proppant, gravel pack, roofing granules and abrasive blast materials. Non-ferrous smelting slag is treated with silica, alumina, calcia and magnesia and then heated for a period of time sufficient for reaction of the ingredients and homogenization prior to being made into granular products.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Patent Application No. 60/829,481 filed Oct. 13, 2006, which is incorporated herein by reference in its entirety.

BACKGROUND

1. Technical Field

This invention relates to granular products, more specifically proppant and gravel pack particles, roofing granules and abrasive blast media prepared from a feedstock of non-ferrous metal smelting slag together with a minor proportion of ceramic oxide additives; and a method of making the same.

2. Description of the Related Art

Proppants are used in hydraulic fracturing of subterranean oil and gas bearing geological formations. Proppants are entrained in a fluid specially prepared for characteristics of flow, with adjusted viscosity, and are forced down a borehole under pressure, the pressure being sufficiently high to hydraulically fracture the underground formation and then propagate that fracture out into the geological formation. After fracture of the oil or gas bearing formation, and upon release of the closure pressure, proppant particles remain behind in the fractures to prop the fractures open, thus increasing the flow of oil or gas out of the formation and into the borehole. In this way, production of oil and gas is enhanced.

A proppant material is normally a ceramic material, such as silica sand, or engineered proppants such as aluminosilicates, and other alumina containing ceramics. Proppants are selected for use based upon crushing strength. The use of a particular ceramic proppant may be limited by the creation of fines from crushing during use, and by chemical processes that dissolve the proppant particles. Estimates of proppant performance in actual conditions of use are made under laboratory conditions with crushing tests and conductivity-permeability tests. Silica sands are commercially used up to 5,000 psi above which fines generation is excessive. Aluminosilicates are used in the form of lightweight proppants of intermediate density up to pressures of 5,000-10,000 psi and high alumina proppants up to pressures of 20,000 psi.

Gravel packing is a technique useful to reduce migration of fine particles into the borehole and acts in this capacity as a filter material. Gravel material is held in place in the borehole with a screen. Coarse silica particles and round aggregate traditionally are used in gravel pack application. Carrier fluids are used to transport gravel packing to the subterranean formation where the pack then is deposited.

A primary consideration of all gravel pack materials and proppants is cost. For example, about 50-250 tons of proppants and gravel pack are typically required to stimulate production of an average well. And, all of the ceramic proppant materials now marketed are far more expensive than sands.

Aluminosilicates and high alumina proppants generally are costly owing to high raw material cost and processing cost. Alumina-bearing industrial minerals, particularly bauxites, are expensive. Material preparation steps include fine grinding and milling, which are typically associated with high processing costs and inherently low production rates. (See, e.g., U.S. Pat. Nos. 4,068,718; 4,427,068; and 4,522,731.) U.S. Pat. No. 4,555,493 teaches crushing and wet grinding preparation steps; U.S. Pat. Nos. 4,713,203 and 5,175,133 teach the use of a very fine particle fraction obtained from high grade bauxite ore as having the advantage of high reactivity and higher sintering rates. While high reactivity of fine ceramic oxides is well known to aid sintering of alumina, the resulting compounds are also very expensive and usually reserved for the production of high grade technical ceramics.

Almost all manufacturing processes for aluminosilicate and high alumina ceramic proppants employ a costly firing step by rotary furnace processing at sintering temperatures of 1300-1400° C. (U.S. Pat. No. 6,753,299). Low cost clay and bauxite raw materials are described in U.S. Pat. Nos. 6,753,299, 4,555,493, and 7,036,591. However, these approaches have the limitation of requiring that hydrated minerals such as kaolinite (Al₂O₃.2SiO₂.2H₂O) and gibbsite (Al₂O₃.3H₂O) as substitutes for calcined bauxite pay the energy penalty of water elimination during firing. Even if a proppant is derived from a spent aluminosilicate ceramic media, the crushing, grinding, and firing steps still must be performed, which can increase the actual production costs.

Another costly processing requirement of making all aluminosilicate proppants is the development of strength in the end product. During firing of a ceramic, a liquid phase is produced. For aluminosilicate and high alumina ceramics, the liquid phase is usually corundum, mullite, or a vitreous silica-rich phase. During cooling, the vitreous phase may remain, or the vitreous phase may be recrystallized to form a microcrystalline structure as is well known to ceramic art. Alternatively, feldspar, wallastonite or wallastonite-formers, and fused bauxite dust may be used to develop a vitreous phase. No matter which approach is taken, there still is the burden of high firing cost to develop strength in the final ceramic body.

Yet another approach (U.S. Pat. No. 5,175,133) teaches the use of a reinforced composite design, in which the aluminum metal is reinforced with ceramic microspheres. This approach has the drawback of high cost of metal additive as well as low chemical durability of common metals in high and low pH geological formation environments.

Techniques commonly employing very fine particulate high alumina clays and bauxite have been offered as requiring lower firing costs by making the raw material more reactive during firing, see, e.g., U.S. Pat. No. 5,175,133. However, fine particulate preparations such as fine grinding and wet milling necessarily increase the cost of raw materials substantially.

U.S. 2005/0096207 A1 describes an approach for low temperature processing (about 200° C.) using the sol-gel technique for forming aluminosilicate and phosphate precursors and the use of waste material fillers. However, sol-gel precursors are themselves expensive binding agents, and so the overall product cost is likely to be high.

U.S. Pat. No. 6,372,678 describes the use of spent catalysts, in which FCC (fluid cracking catalyst) petroleum refining catalyst is used as a source of aluminosilicate. This approach may have lower initial raw material sources; however, the process still requires crushing, grinding, agglomerating and firing of proppant spheres. All of these processes add cost to the end product.

U.S. Pat. No. 4,607,697 describes forming proppant particles by blowing a stream of molten material from a base of zircon and silica. However, zircon is tremendously expensive, the price being driven by refractory use and the generally low commercial availability due to a controlled market.

BRIEF SUMMARY

Certain embodiments describe a very low-cost process for making granular products, and products of substantially spherical geometry for use as proppants and gravel pack.

More specifically, non-ferrous metal smelting slag is used as a low cost raw material. The slag may be utilized as cold slag with or without crushing to enable a particle size useful in forming a batch capable of melting in a commercial melting furnace.

The present invention utilizes non-ferrous metal smelting slag as a major component or base material for producing proppant and gravel. Non-ferrous metal slag is produced during the smelting of copper, lead, zinc, cadmium, nickel, and other non-ferrous metals. Usual commercial practice is the water granulation of molten slag. Non-ferrous metal slag particles from water granulating practice that have not been combined with additives or other chemical modification display low strength. Particles are so soft as to be useless where crushing strength above about 1000 psi is required.

It has been discovered that when suitable ceramic material additives are mixed with slag in the correct proportions, then crushing strength and chemical durability are enhanced considerably. The slag becomes a ferrosilicate glass when modified correctly with ceramic additives. It is this glass structure that becomes so useful after modification.

Slags which have not been chemically conditioned seldom prove useful in commerce, as evidenced by the enormous piles of slag adjacent smelter sites.

Non-ferrous slag currently has few end uses of any real value. Small amounts are utilized as an iron oxide additive to Portland cement for the purpose of boosting iron silicate content or as a raw material for preparing abrasive blast material. These uses are more a consequence of an effort to remove or dispose of slag from a smelter property than a commercially significant byproduct recovery program capable of totally eliminating slag disposal on the land.

Another embodiment describes a process to use molten slag from a smelting furnace poured directly in to a glass melter where ceramic additives are added and incorporated in to the melt. This technique has the advantage of energy conservation of the molten slag ingredient.

A further embodiment describes the use of common, low cost industrial mineral additives such as limestone, dolomite, magnesite, silica sand and silica rock, aluminous clays, recycled refractories, and the like, as sources of calcia, magnesia, silica and alumina.

Advantageously, the processes described herein eliminate the need to crush and grind raw materials. Raw materials of large particle size (about ⅜ inch mesh and smaller) can be used to prepare proppant melts.

A further embodiment provides a process where large tonnages of end product can be inexpensively made by atomization of a molten stream of ferrosilicate glass using air, water vapor or both as the blowing medium to produce spherical particles.

Yet another embodiment provides glass making technology and chemistry design so that ordinary variations in the chemical makeup of smelter slag do not cause disruption of the process of making proppants, gravel pack, and granular products. Glass technology is well proven for the ability to absorb chemical variation. End products may display variation in chemical composition, but important specifications of crushing strength and chemical durability are unaffected. Ceramic processes which produce polycrystalline materials are vulnerable to formulary variation since the result of these non-stoichiomietric formulations is the presence of unwanted secondary crystalline phases.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows long-term conductivity and permeability test results of a proppant composition prepared according to a method described herein.

FIG. 2 shows comparative data on conductivities of a proppant sample described herein (sample T-2 20/40 mesh) with that of white sand, duel resin coated and premium resin coated sand, economy light weight engineered ceramic proppant and high strength bauxite engineered ceramic proppant.

DETAILED DESCRIPTION

In nature, metal ores are often found in impure states. The metals may be oxidized, sulfidized, or mixed in with silicates of other metals. Smelting is a form of extractive metallurgy, which isolates the metal from its ore. Smelting is typically carried out at temperatures higher than the melting point of the metal. The impurities in the metal ore are thus separated from the molten metal and can be removed. The collection of compounds that is removed is called “smelter slag” or “slag”.

Different smelting processes produce different slags. In general, the slags can be classified as non-ferrous or ferrous. Non-ferrous smelting slag is an end product from smelting metal ores containing lead, zinc, copper, cadmium and numerous other non-ferrous metals. These non-ferrous metal ores typically contain iron and silica as impurities. The smelting process separates these impurities from the non-ferrous metals. The separated impurities are removed in the form of ferrosilicate based slags. Unless indicated otherwise, the slag described herein refers to the ferrosilicate impurities or by-product collected from smelting non-ferrous metal ores.

More specifically, the smelting process is normally carried out in batch operated converting furnaces. Slag is usually tapped from a smelter furnace at the end of each batch smelting episode. The slag stream is often water quenched as preferred practice to form granules that can be easily handled after dewatering. Far less frequent practice is pouring of slag directly onto the ground to cool and harden.

Slag that has been rapidly cooled as in quenching displays an amorphous or glassy microstructure. Slag that has been cooled slowly exhibits crystalline microstructure. Slag feed material of either amorphous or crystalline microstructure may be used interchangeably in the instant process. The most useful approach in making proppant or gravel pack is to pour molten slag directly from the smelting furnace into a converting furnace where ceramic raw materials may be added to enhance the conversion into proppant and, moreover, for the purpose of creating an end product with properties superior to smelter slag alone. Use of hot slag reduces the energy required to prepare a melt ready for atomization as spherical proppant particles. Alternatively, cold slag may be remelted and modified with minor additions of ceramic raw materials to form a melt.

A proppant or gravel pack material can be prepared from solidified or molten slag amended with a minority of inexpensive industrial minerals. Due to the low cost of the slag, the proppant or gravel pack material can be commercially offered for sale at a price similar to the combined cost of raw material plus crushing and grinding preparation steps for aluminosilicates and alumina based ceramic proppants before the agglomeration or firing and sintering steps.

Thus, one embodiment provides a ferrosilicate glass formed by non-ferrous slag modified with ceramic oxides, which impart commercially important properties. For example, silica additive (e.g., ceramic oxides) imparts strength to the ferrosilicate structure by increasing the number of silica atoms in the ferrosilicate glass network. Addition of lime modifies the structure further to impart glass quality and enable better forming properties, and make favorable melt dynamics. Additions of alumina increase mechanical strength, increase chemical durability, and promote better forming properties. Additional magnesia promotes high chemical durability and enhanced melt dynamics.

Non-ferrous metal smelting slags are suitable subjects for process feed materials since they vary in metal oxide content by a small amount. Typical chemical analysis variation over time is about the same as found in industrial minerals.

An efficient glass melting furnace operated as an all-electric melter, a fossil fuel fired melter, or alternatively a melter that uses electric melting and fossil fuel top firing can be used. A rotary furnace, though suitable, is not required to prepare the melts.

Proppant forming technique can utilize atomization processes which are inexpensive to operate because a molten stream of proppant is provided by a glass melter. An additional benefit of the instant process is the availability of molten slag handling equipment such as slag train cars and specialized slag trucks used to remove the molten slag from the direct confines of the smelter property.

No particle agglomeration process is required as a result of employment of the atomization technique.

Alternatively, granules for roofing granule and abrasive blast media applications may be made by quenching a molten stream of product in a water jet apparatus. Production of granules can be arranged as an adjunct process to atomization.

The present invention further provides a proppant composition comprising about 60-90 weight percent non-ferrous metal smelter slag and 10-40 weight percent of one or more additives including calcia, alumina, magnesia and silica.

The presence of typical contaminant compounds contained in slag does not prove detrimental to the end product manufacture or specification. For example, smelter slags normally contain small amounts of metals such as copper, lead, zinc, cadmium, chromium, sulfur, tellurium, zirconium, arsenic, cobalt, manganese, antimony, nickel, tin, strontium, barium, titanium, germanium, fluorine, chlorine, potassium, sodium and others. Minor contaminants are not detrimental to the process of making granules or spherical particles. Glass systems have been abundantly shown to be capable of accommodating minor ingredient contaminants without detriment as is well known in glass technology.

The present invention provides a ferrosilicate glass that has been shown to produce a commercially viable product even though the smelter slag chemistry has varied to the full limit of smelter specification. The formulation has incorporated into it, by design, sufficient glass formers and modifiers to absorb smelter slag chemistry variation.

Table I shows typical chemical analysis for non-ferrous metal smelting slags. TABLE I Chemical Analysis of Typical Non-Ferrous Metal Smelting Slag WEIGHT PERCENT OXIDES FeO Fe₂O₃ SiO₂ Al₂O₃ CaO MgO Balance Slag No. 1 50.5 3.5 34.3 3.0 2.0 1.5 5.2 Slag No. 2 33 6 29.5 3.4 20.5 1 6.6

Slags of chemistries shown in Table I are interchangeable in formulations; interchangeability of slags within formulations can be accomplished by balancing the oxide component formulation by addition or subtraction of additive ingredients such as silica (SiO₂), calcia (CaO), alumina (Al₂O₃) or magnesia (MgO).

The present invention further provides a proppant composition comprising at least one of the following additives:

Silica addition 0-15 weight %

Calcia addition 0-20 weight %

Alumina addition of 0-20 weight %

Magnesia addition of 0-10 weight %

The additives may be purchased as raw material, which are readily available granular or powdered products. For example, raw material in mesh sizes of ¼ inch and smaller have been found to be beneficial. Smaller particle sizes have the advantage of higher reactivity than the larger sizes and this higher reactivity may provide lower energy input as well as shorter processing times. Other preparation steps such as milling or grinding are not necessary beyond the typical manufacturer's grade for glass preparation.

Ordinary industrial mineral sources for silica, calcia, alumina and magnesia may be used in formulations. These raw materials may contain iron oxide contamination. Allowance of iron contamination can be used as an opportunity to use very low cost raw materials. For example, impure bauxite and alumina bearing clays containing 10 weight percent or more of iron oxide contamination may be used as alumina sources. Iron oxide contamination can be useful for formation of ferrosilicates. Impure limestone, magnesite and dolomite may be used as sources of calcia and magnesia. Silica sources can be lowest quality glass making grade silica sands or feldspathic sands containing 10 weight percent of iron oxides. Alternatively, recycled refractory brick and other industrial byproducts can be useful as sources for alumina, silica, magnesia and calcia where aluminosilicate brick and basic brick from non-ferrous metal smelting and steelmaking serve as examples.

A reducing agent (or reductant) can be used to reduce the iron oxide contaminant. Reductant sources include anthracite coal granules or other granular coal sources where the ash content of the coal may exceed 10 weight percent and particle size ¼ inch and smaller. Coke breeze and reject coke from the petrochemical industry may be useful and inexpensive sources of reductants as well as scrap graphite.

Formulation of a glass batch can be accomplished by use of standard commercial batch plant technology. A simple unjacketed ribbon blender may be useful for blending batch ingredients for example.

Addition of raw batch to a melter is most easily accomplished with a conveying auger with or without a water-cooled outer barrel. Standard glass batch charging equipment is useful for filling operations or to maintain melter level.

Melts from cold slag or molten slag source, or both, may be operated either in a batch mode or in a continuous mode. The process of the instant invention is well suited to batch or continuous melting.

Melting energy may be supplied by fossil fuels or by electric melting; or a combination of the two as normally found useful in the glass industry.

A preferred melting system is a melter employing submerged electrodes together with top fire from natural gas or oil burners. This melting configuration can be applied to an intermittent batch operation or continuous melting operational approach.

Melter designs may be acquired through the same manufacturers who build the smelting furnaces or those firms who supply glass melting equipment designs. Melter design may employ refractory linings, a water cooled wall construction; or a combination of both.

When continuous melting is preferred, a refractory throat cover block or water cooled throat plate can be useful to separate melting and refining chambers.

Preferred technology for electrode materials has proven the use of graphite, molybdenum, and certain refractory alloys. Electrode holder designs are most typically those designs used in the metal melting and smelting industries or those used in glass manufacturing melters.

A melting temperature required for incorporation of additive ingredients is 1150-1500° C.

Melter area design on the basis of commercial melter specification is 2.0-10.0 square feet per short ton of cold raw material addition to the melter. Laboratory melts can be adjusted accordingly to obtain similar results. A commercial melting furnace may be configured as a batch type melter or continuous melter. A preferred all electric melting system used molybdenum vertical electrodes, a submerged throat wall and operated on 2.6 square feet per ton production.

A preferred melting system used a 30-ton all-electric melter averaging 750 kwh per ton and could be operated at 2.6 square feet per ton to produce melts at 1375° C. Feedstock slag was simulated with iron oxides and other minerals, additives were minus 30 mesh industrial minerals and additive level was 30 weight percent. It was found by equipment operation that a melting temperature of 1375° C. produced the best production throughput for the equipment in use and that production economies were maximized. Further, the melt was held below temperatures where foaming incidents were known to occur; foaming events totally disrupt production. Electrode material was molybdenum and graphite in a vertical electrode holder using commercial water cooled design. No top fires were used. Batch was fed from a storage hopper to the melter batch blanket using a 10 inch screw conveyor and melter level maintained through a timing circuit capable of modulating batch feeding time together with the screw conveyor flight speed. Melting at the prescribed rate provided for entire melting to occur together with complete homogenization so that a very good state of chemical refinement had occurred and that no further chemical homogenization was required during the subsequent refining step.

Another preferred melting system is an all-electric melter, wherein the slag is added either as a molten stream or as slag granules and where the melt is intentionally held below temperatures in the range of 1375-1400° C. for the express purpose of holding sulfur compounds in the slag. At processing temperatures above 1400° C. it will be found that the sulfur dioxide, sulfur trioxide and hydrogen sulfide are gassed from the melt and that this gassing may be objectionable to environmental health.

Molten ferrosilicate was discharged from the melter through a short forebay which contained a consumable and replaceable orifice plate which metered out the amount of product entering a combination refining and forehearth chamber. The purpose of the refining and forehearth chamber was to homogenize the melt with respect to temperature alone. Refining may be carried out in a forehearth section of a melting apparatus as normally done in the glass industry. Homogenization can be enhanced with stirring equipment and bubblers if deemed desirable.

Refining can be carried out at a temperature of 1150-1500° C. for a time sufficient to homogenize the melt thermally and chemically. Melting and refining should be carried out at a temperature sufficient to maintain good melt and refining progress while not so high a temperature as to cause foaming. For example, a melt may be prepared as a batch. After melting, the melt can be brought to a uniform bath temperature at which forming of granule products or spherical proppant particles can occur at the optimum condition of particle size, geometry, surface quality, and other condition of specifications for end products.

A preferred refining system used an electrically heated refining chamber. The refiner was fitted with a consumable and replaceable orifice ring. The refining chamber was designed on a basis similar to a glass industry forehearth, with long aspect ratio. Refining temperature was 1300° C. The refiner also served the purpose of temperature conditioning so that the melt product could be brought to a preferred process temperature for forming in to a granule or a spherical particle. Temperature control was available to give about 5° C. pouring temperature accuracy from the orifice ring. In this way, excellent melt temperature-viscosity relationships could be managed as a part of the process control.

Melt product exiting the refining chamber may be directed to forming processes which are grouped together. An atomization system can be located directly under the refining chamber so that the melt stream exiting the orifice drops directly through the blowing apparatus. Alternatively, a granulation system can be located below the orifice ring.

A preferred method is to use both atomization and granulation systems so that the gravity flow of the melt stream exiting the orifice ring is first dropped through the atomization apparatus. If the atomization step is not chosen, the melt can be granulated in a quench trough. For example, an atomization apparatus using air and steam as the media forming jet was located above a granule forming quench trough equipped with primary water nozzles for forming the granule together with conveying water nozzles used to remove the product from the production area to dewatering, drying, sizing and storage. Proppant material was atomized and directed into a blowing chamber, gathered and subsequently separated into commercial product sizes.

The following specific examples are offered by way of illustration and not by way of limitation.

EXAMPLE 1

Technical grade calcined bauxite, glass grade silica sand, agricultural limestone and agricultural grade dolomite were used to prepare a batch. Particle size of raw materials was typically minus 30 mesh and smaller as selected to give rapid melting performance. Care was taken to choose melt ingredients which would produce a melt in a time period short enough to be unaffected by the dissolution of crucible refractory material. Wood charcoal crushed to minus 100 mesh was used as the reductant. Batch T-1 slag no. 2 84.3 parts 590.1 grams calcined bauxite 6.3 44.1 lane mt. silica sand 2.8 19.6 dolomite 2.13 14.9 limestone 9.36 65.5 wood charcoal 1.0 7.0

Batch was weighed out on a platform gram scale. Batch contents were mixed in a rotary drum mixer for 5 minutes and until no segregation of batch materials was evident. After packing the batch material into a fire clay crucible fitted with a refractory lid, the crucible was loaded in an electrically heated kiln previously brought to 1260° C. The purpose of the refractory crucible lid was to maintain ferrous iron content and prevent oxidation of the ferrous iron content to ferric iron. The crucible contents were examined after a period of one hour at 1260° C. ambient kiln temperature to verify thorough melting. Care was taken not to allow melt episodes to continue so long that alumina and silica from the crucibles would be dissolved and taken up in to the melt. An inconel stir rod was used to check chemical homogeneity of the melt and to help homogenize the melt with respect to thermal condition. Within 45 minutes of stirring the melt was poured, after verification of thermal and chemical homogeneity, into a proppant and gravel pack atomization apparatus. Spherical particles were collected in a blowing chamber during blowing, removed and screened, and then submitted for testing to a commercial laboratory knowledgeable in proppant testing procedures.

Testing was performed by Stim-Lab, Inc, a third party laboratory with experience in testing proppant materials per American Petroleum Institute practices as outlined in test procedure API RP 60 for crush test performance and API RP 61 for long-term conductivity performance analysis.

Table II shows the test results for samples of 20/40 mesh proppant tested at 5,000 psi, and 7,500 psi. As can be seen in Table II, sample T-1 produced a satisfactory crush test at 5,000 psi. This test illustrates that Sample T-1 would perform as well or better than silica sand in crush tests. The 40/70 mesh fraction passed testing at 5000 and 7500 psi, indicating that this fraction exceeds silica sand performance and is comparable to other engineered ceramic proppants. The 16/20 mesh fraction passed 5000 psi tests, indicating performance superior to that of silica proppants. Sphericity and roundness per the Krumbein Chart utilized in API RP 60 gave ratings of 0.84 and 0.86 sphericity and roundness respectively for the 20/40 mesh fraction, while the 40/70 fraction was estimated at 0.87 and 0.90 sphericity and roundness, the 16/20 mesh fraction exhibiting 0.79 and 0.82 sphericity and roundness; all well within the acceptable limit of 0.70 per API RP 60. TABLE II Crush Test Performance of Sample T-1 in sizes 20/40 mesh, 40/70 mesh, and 16/20 mesh. Maximum fines for 20/40 ceramic proppant per API RP 60 = 10%; maximum fines for 40/70 ceramic proppant = 5%; maximum fines for 16/20 mesh ceramic proppant = 25%. PSI % FINES 20/40 Mesh Sample 5000 2.4 7500 12.1 20/40 40/70 Mesh Sample 5000 0.6 7500 2.1 10000 5.1 20/40 16/20 Mesh Sample 5000 16 7500 33.6

EXAMPLE 2

The batch and melt were prepared as in Example 1, except that the batch was melted for 1.5 hrs and refined at 1315° C. for 0.5 hrs. Batch T-2 slag no. 2 78.9 parts 552.3 grams calcined bauxite 7.0 49.0 lane mt. silica sand 1.6 11.2 dolomite 1.6 11.2 limestone 8.86 62.02 wood charcoal 1.0 6.0

Testing was performed by Stim-Lab, Inc, a third party laboratory with experience in testing proppant materials per American Petroleum Institute practices as outlined in test procedure API RP 60 for crush test performance and API RP 61 for long-term conductivity performance analysis.

Table III shows the test results for samples of 20/40 mesh proppant. As can be seen in Table III, sample T-2 produced a satisfactory crush test at 5,000 psi and at 7,500 psi. This test result illustrates that Sample T-2 would perform better than silica sand and similarly to light-weight engineered ceramic proppant in crush tests. The 40/70 mesh fraction passed tests at 5000 and 7500 psi indicating that this fraction exceeds silica sand performance and is comparable to other engineered ceramic proppants. The 16/20 mesh fraction passed 5000 psi tests as well as 7500 psi tests, indicating performance superior to that of silica proppants and similar to engineered lightweight ceramic proppants. Sphericity and roundness per the Krumbein Chart utilized in API RP 60 gave ratings of 0.87 and 0.89 sphericity and roundness respectively for the 20/40 mesh fraction, while the 40/70 fraction was estimated at 0.88 and 0.90 sphericity and roundness, the 16/20 mesh fraction exhibiting 0.83 and 0.85 sphericity and roundness; all well within acceptable limits of 0.70 per API RP 60. TABLE III Crush Test Performance of Sample T-2 in sizes 16/20 mesh, 20/40 mesh and 40/70 mesh. Suggested maximum fines for 20/40 ceramic proppant per API RP 60 = 10%; maximum fines for 40/70 ceramic proppant = 5%; maximum fines for 16/20 mesh ceramic proppant = 25%. PSI % FINES 20/40 Mesh Sample 5000 1.9 7500 8.7 10000 14.7 40/70 Mesh Sample 5000 0.4 7500 0.9 10000 6.0 16/20 Mesh Sample 5000 5.2 7500 20.2 10000 35

EXAMPLE 3

The batch and melt were prepared as in Example 1. Batch T-3 slag no. 2 84.7 parts 592.9 grams calcined bauxite 6.0 42.0 lane mt. silica sand 1.6 11.2 dolomite 3.63 25.41 limestone 13.25 92.75 wood charcoal 1.0 6.0

Testing was performed by Stim-Lab, Inc, a third party laboratory with experience in testing proppant materials per American Petroleum Institute practices as outlined in test procedure API RP 60 for crush test performance and API RP 61 for long-term conductivity performance analysis.

Table IV shows the test results for samples of 20/40 mesh proppant. As can be seen in Table IV, sample T-3 produced a satisfactory crush test at 5,000 psi and at 7,500 psi. This test illustrates that Sample T-3 would perform better than silica sand in crush tests and similar to engineered lightweight ceramic proppants. The 40/70 mesh fraction passed testing at 5000 and 7500 psi indicating that this fraction exceeds silica sand performance and is comparable to other engineered lightweight ceramic proppants. The 16/20 mesh fraction passed 5000 psi tests indicating superior performance to silica proppants. Sphericity and roundness per the Krumbein Chart utilized in API RP 60 gave ratings of 0.88 and 0.87 sphericity and roundness respectively for the 20/40 mesh fraction while the 40/70 fraction was estimated at 0.88 and 0.89 sphericity and roundness, the 16/20 mesh fraction exhibiting 0.85 and 0.87 sphericity and roundness; all well within acceptable limits of 0.70 per API RP 60. TABLE IV Crush Test Performance of Sample T-3 in sizes 16/20 mesh, 20/40 mesh and 40/70 mesh. Suggested maximum fines for 20/40 ceramic proppant per API RP 60 = 10%; maximum fines for 40/70 ceramic proppant = 5%; maximum fines for 16/20 mesh ceramic proppant = 25%. PSI % FINES 20/40 Mesh Sample 5000 1.1 7500 9.1 10000 21.8 40/70 Mesh Sample 5000 0.6 7500 1.9 10000 7.9 16/20 Mesh Sample 5000 12.7 7500 33.1

EXAMPLE 4

The batch and melt were prepared as in Example 1, except that the melt was conducted for 1.5 hrs at 1400° C. and refined at 1400° C. for a period of 0.5 hr. Batch G-3 slag no. 2 90.9 parts 636.3 grams calcined bauxite 6.0 42.0 dolomite 7.14 49.98 wood charcoal 1 6

Testing was performed by Stim-Lab, Inc, a third party laboratory with experience in testing proppant materials per American Petroleum Institute practices as outlined in test procedure API RP 60 for crush test performance and API RP 61 for long-term conductivity performance analysis.

Table V shows the test results for samples of 20/40 mesh proppant. As can be seen in Table V, sample G-3 produced a satisfactory crush test at 5,000 psi. This test illustrates that Sample G-3 would perform better than silica sand in crush tests. The 40/70 mesh fraction passed testing at 5000 and 7500 psi and 10,000 psi tests, indicating that this fraction exceeds silica sand performance and is comparable to other engineered ceramic proppants. Sphericity and roundness per the Krumbein Chart utilized in API RP 60 gave ratings of 0.86 and 0.87 sphericity and roundness respectively for the 20/40 mesh fraction while the 40/70 fraction was estimated at 0.88 and 0.89 sphericity and roundness; all well within acceptable limits of 0.70 per API RP 60. TABLE V Crush Test Performance of Sample G-3 in sizes, 20/40 mesh and 40/70 mesh. Suggested maximum fines for 20/40 ceramic proppant per API RP 60 = 10%; maximum fines for 40/70 ceramic proppant = 5%; maximum fines for 16/20 mesh ceramic proppant = 25%. PSI % FINES 20/40 Mesh Sample 5000 3.7 7500 12.4 40/70 Mesh Sample 5000 1.1 7500 3.1 10000 4.9 12500 12.5

EXAMPLE 5

The batch and melt were prepared as in Example 1. Batch I-1 slag no. 2 88 parts 616 grams calcined bauxite 7.0 49 limestone 9.0 63 wood charcoal 1.0 6

Testing was performed by Stim-Lab, Inc, a third party laboratory with experience in testing proppant materials per American Petroleum Institute practices as outlined in test procedure API RP 60 for crush test performance and API RP 61 for long-term conductivity performance analysis.

Table VI shows the test results for samples of 20/40 mesh proppant. As can be seen in Table VI, sample 1-1 produced a satisfactory crush test at 5,000 psi and 7,500 psi. This test illustrates that Sample 1-1 would perform better than silica sand in crush tests and similar to engineered light weight ceramic proppants. The 40/70 mesh fraction passed testing at 7500 and 10,000 psi, indicating that this fraction exceeds silica sand performance and is comparable to other engineered ceramic proppants. The 16/20 mesh fraction passed tests at 5000 and 7500 psi, in accordance with results for engineered lightweight ceramic proppants. Sphericity and roundness per the Krumbein Chart as utilized API RP 60 gave ratings of 0.86 and 0.89 sphericity and roundness respectively for the 20/40 mesh fraction while the 40/70 fraction was estimated at 0.88 and 0.89 sphericity and roundness; the 16/20 fraction displaying 0.80 and 0.85 sphericity and roundness; all well within acceptable limits of 0.70 per API RP 60. TABLE VI Crush Test Performance of Sample I-1 in sizes 16/20 mesh, 20/40 mesh and 40/70 mesh. Suggested maximum fines for 20/40 ceramic proppant per API RP 60 = 10%; maximum fines for 40/70 ceramic proppant = 5%; maximum fines for 16/20 mesh ceramic proppant = 25%. PSI % FINES 20/40 Mesh Sample 5000 0.8 7500 5.2 10000 17.6 40/70 Mesh Sample 7500 0.5 10000 2.5 16/20 Mesh Sample 5000 3.3 7500 22.6

FIG. 1 shows long-term conductivity and permeability test results in accordance with API RP 61 as provided by Stim-Lab, Inc. Note that 1-1, T-2 and T-3 20/40 mesh samples showed similar conductivity and permeability results.

FIG. 2 shows a comparison of conductivity for sample T-2 20/40 mesh proppant and white sand, duel resin coated and premium resin coated sand, economy lightweight engineered ceramic proppant and high strength bauxite engineered ceramic proppant. Proppant T-2 gave superior results in comparison to white sand. T-2 proppant also outperformed resin coated materials at higher pressures. As pressure was increased on the test cell, degradation of performance was less for the T-2 sample in comparison to the lightweight and high strength bauxite engineered ceramic proppants.

All of the above U.S. patents, U.S. patent application publications, U.S. patent applications, foreign patents, foreign patent applications and non-patent publications referred to in this specification and/or listed in the Application Data Sheet, are incorporated herein by reference, in their entirety.

From the foregoing, it will be appreciated that, although specific embodiments of the invention have been described herein for purposes of illustration, various modifications may be made without deviating from the spirit and scope of the invention. Accordingly, the invention is not to be limited except as by the appended claims. 

1. A process for making a granular product, comprising: mixing a non-ferrous metal smelting slag with one or more oxide additives to form a mixture, wherein the oxide additive is calcia, silica, alumina or magnesia; melting the mixture at temperatures of 1150-1500° C.; refining the melted mixture to achieve thermal and chemical homogeneities at temperatures of 1150-1500° C.; and forming the refined mixture into substantially spherical particles or granules.
 2. The process of claim 1 wherein the smelting slag is derived from smelting non-ferrous metals, wherein the non-ferrous metal is copper, lead, zinc or cadmium.
 3. The process of claim 1 wherein the slag displays an amorphous microstructure or a polycrystalline microstructure.
 4. The process of claim 1 wherein the melted mixture is atomized in air or air/steam, or water quenched.
 5. The process of claim 1 wherein the melting is carried out at a temperature of about 1275° C.
 6. The process of claim 1 wherein the melting is carried out at a temperature of about 1400° C.
 7. The process of claim 1 wherein the melted mixture is refined with respect to chemical and thermal homogeneity at about 1315° C.
 8. The process of claim 1 wherein the melted mixture is refined with respect to chemical and thermal homogeneity at about 1400° C.
 9. The process of claim 1 wherein the oxide additives are industrial raw materials that contains iron oxide contaminant up to 10 wt %.
 10. The process of claim 2 wherein the non-ferrous slag contains one or more typical contaminants, the contaminant being copper, lead, zinc, arsenic, antimony, cobalt, cadmium, chromium, manganese, nickel, fluorine, chlorine, germanium, sodium, tin, tellurium, potassium, barium, strontium, titanium, sulfur or zirconium.
 11. The process of claim 2 wherein the slag may be added to the melting process as a dry granule or as a molten material as directly drawn from a smelting furnace.
 12. The process of claim 1 wherein the melting is carried out in an electric melter where sulfur oxides are retained in the melt.
 13. The process of claim 1 wherein the silica is an industrial grade silica sand or feldspathic sand.
 14. The process of claim 1 wherein the calcia is industrial or agricultural grade limestone or dolomite.
 15. The process of claim 1 wherein the magnesia are industrial or agricultural grade dolomite or magnesite.
 16. The process of claim 1 wherein the alumina is industrial grade alumina or impure bauxite or impure industrial grade clays.
 17. The process of claim 1 wherein the magnesia, calcia, silica and alumina are spent refractory from one or more industrial sources, wherein the industrial source is non-ferrous metal smelting, steelmaking or glassmaking.
 18. The process of claim 1 wherein the granular product is a proppant material, a gravel pack granule, an abrasive blast material, or a roofing granule material,
 19. A composition comprising: a non-ferrous metal smelting slag; and one or more oxide additives, wherein the oxide additive is alumina, silica, magnesia or calcia.
 20. The composition of claim 19 wherein the non-ferrous metal smelting slag and the one or more oxide additives form ferrosilicate.
 21. The composition of claim 19 wherein the oxide additive further comprises iron oxide contaminant.
 22. The composition of claim 21, further comprising a reducing agent.
 23. The composition of claim 22 wherein the reducing agent is carbon-based.
 24. The composition of claim 23 wherein the alumina is an industrial grade alumina, impure bauxite or industrial grade clay, the calcia is industrial or agricultural grade limestone or dolomite, the magnesia is industrial or agricultural grade dolomite or magnesite, and the silica is industrial grade silica sand or feldspathic sand. 